1. Field of the invention
The present invention relates to a terminal switching control apparatus for a communication terminal having a voice terminal device and a non-voice terminal device which exercises a switching control between the voice terminal device and the non-voice terminal device.
2. Description of the Prior Art
A system combining a voice terminal device and a non-voice terminal device, such as a combination of a telephone set and a facsimile tranceiver, has come into wide use in a telephone communication system, where the voice terminal device and the non-voice terminal device share a common telephone line. In case the voice terminal device is a telephone set and the non-voice terminal device is a facsimile tranceiver, the facsimile tranceiver is normally given a priority in such a manner that the telephone system is automatically connected to the facsimile device when the telephone bell rings upon arrival of a call signal. Then, the calling party tends to be confused and frustrated hearing over the phone only the automatic facsimile answer back tone while no voice contact is established with the called party. On the other hand, the called party also has inconvenience in that no voice call can be received when the facsimile device is set for the automatic reception mode.
The U.S. Pat. No. 4,584,434, issued Apr. 22, 1986 to Hashimoto, teaches a system added to a communication terminal which enables a facsimile device to receive information in response to a remote control signal transmitted from the calling side when no person is present at the called side. However, such a conventional remote controlled switching system requires a transmission of a predetermined push-button code signal from the calling side in order to activate the switching to the facsimile device at the called side. Therefore, in such a system, if the calling party does not know the particular code, the connection to the facsimile device at the called side will not be achieved and the information will not be transmitted to the called side.
The applicant's international application, No. PCT/JP86/00404, laid open to the public Dec. 17, 1987, discloses a terminal controller which automatically switches a connection between a telephone set and a facsimile device without using any particular code transmitted from the calling side.